Southern California -- this just in

A car with ammunition inside was engulfed in flames Monday night after a multi-vehicle collision that shut down all lanes on the westbound 60 Freeway in Monterey Park.

The accident occurred shortly before 9:30 p.m. west of Greenwood Avenue and may have involved about half a dozen vehicles, according to the California Highway Patrol.

Traffic was snarled back to the 605 Freeway, but the CHP was hoping to open the lanes by about 10:30 p.m.

[Updated at 10:53 p.m.: All lanes have been reopened, the CHP said.]

The car with ammunition inside began exploding as rounds went off, creating a temporary threat to responding officers, the CHP said. But the flames were knocked down and the truck was being towed away.

Investigators were responding to the scene. No other details were available.